How Families Should Think About Concentrated Stock

For many high-net-worth families, a concentrated stock position — a large holding in a single company, often representing the majority of their investable wealth — is both the source of their financial success and the most significant financial risk they carry. Managing that concentration intelligently is one of the most consequential investment decisions a family can make.

Concentration can amplify both gains and losses when a single stock performs well or poorly. Families with concentrated positions often hold them long past the point of rational risk management — because of embedded capital gains, because of emotional attachment to the company, or because of uncertainty about how to diversify without a large tax bill.

This guide addresses how families should think through concentrated stock decisions, what strategies are available for tax-efficient diversification, and how estate planning intersects with concentrated positions in ways that most families have not considered.

The Risk of Concentration: Getting the Math Right

A family with $15 million in total wealth, of which $12 million is in a single public company stock, has effectively made a concentrated bet on the performance of one company. This is true regardless of how well-known, how profitable, or how historically successful that company has been. A company once viewed as a permanent fixture can decline sharply during a market cycle, and the timing and magnitude of any future decline cannot be predicted. The risk is real, but its consequences depend on the family's liquidity, obligations, time horizon, and ability to tolerate loss.

The relevant question is not "will this company continue to perform?" — but rather: in an illustrative stress scenario, what would happen to my family's financial situation if this stock lost 50% of its value? That scenario is hypothetical, not a prediction. If the answer is "we are fine," concentration may be a reasonable choice. If the answer is "we cannot maintain our lifestyle, fund our estate plan, or achieve our retirement goals," diversification warrants serious consideration.

The Tax Challenge

The primary objection to diversifying a concentrated stock position is taxes. A family that purchased 100,000 shares at $10 per share and now holds a position worth $120 per share has a cost basis of $1 million and a current value of $12 million — meaning an $11 million unrealized capital gain. Selling the position may trigger federal capital gains tax at up to 23.8% (20% + 3.8% net investment income tax), plus any applicable state taxes. In a high-tax state, the combined effective rate on the gain can exceed 30%.

This creates a real but often overstated objection. Paying 30% in taxes on an $11 million gain still leaves $9.4 million that can be diversified and protected. The alternative — continuing to hold $12 million in a single stock — exposes the entire position to a potential 50% or greater decline. The math of paying taxes to protect against catastrophic loss is usually favorable.

Tax-Efficient Diversification Strategies

Systematic selling over multiple tax years

The simplest approach is a multi-year selling program: realizing gains in amounts that keep the family in a favorable tax bracket each year, gradually reducing concentration over three to seven years. This approach is administratively simple but requires conviction about diversification and willingness to accept ongoing market exposure during the selling period.

10b5-1 plans (for company insiders)

For executives and employees who are insiders of public companies — and subject to trading restrictions — a 10b5-1 plan allows pre-scheduled sales at a time when the insider is not in possession of material non-public information. Properly structured plans provide both a selling mechanism and legal protection for insiders who would otherwise face significant compliance risk.

Charitable diversification

Contributing appreciated shares to a donor-advised fund or charitable remainder trust allows the charitable entity to sell the shares without paying capital gains tax. The donor receives an income tax deduction for the fair market value of the contribution (subject to AGI limitations). For families with philanthropic intent, this is one of the most tax-efficient ways to diversify while also funding charitable goals.

Exchange funds

Exchange funds (also called swap funds) allow investors to contribute concentrated positions to a partnership in exchange for a diversified interest in the partnership, deferring capital gains taxes. These funds typically have minimum investment requirements of $1 million to $5 million or more, lock-up periods of seven years or longer, and specific eligibility requirements. They are a sophisticated tool for the right situation.

Collaring and monetization strategies

Protective puts, zero-cost collars, and prepaid variable forwards can reduce downside risk on a concentrated position without triggering immediate capital gains taxes. These are complex instruments that require careful tax analysis — the IRS has specific constructive sale rules that apply to certain hedging arrangements — but they can provide meaningful protection while the family develops a longer-term diversification plan.

The Estate Planning Dimension

Concentrated stock decisions and estate planning intersect in two critical ways that most families have not fully considered.

The step-up in basis opportunity

If a concentrated stock position is held until death, the cost basis steps up to the fair market value at the date of death — eliminating the embedded capital gain entirely. For families with estate tax exposure, the calculus is complex: the step-up in basis eliminates income tax on the gain, but the full fair market value is included in the taxable estate. For families without estate tax exposure (estates below the exemption), holding appreciated stock until death can be a powerful wealth transfer strategy.

Gifting and trust strategies

Contributing concentrated shares to a GRAT, dynasty trust, or charitable vehicle before selling allows the family to remove the position from the taxable estate at its current value — while the appreciation from the sale passes to heirs (or a charity) tax-free. The timing and coordination of stock position decisions with estate planning transfers can produce significantly better outcomes than treating them as independent questions.